Liquid crystal display device and method of driving the same

ABSTRACT

A liquid crystal display device includes first and second substrates facing each other, a layer of liquid crystal molecules interposed between the first and second substrates, a plurality of color displaying sub-pixels including first, second and third sub-pixels defined on the first and second substrates, first common electrodes in the first, second and third sub-pixels on the first substrate, first pixel electrodes in the first, second and third sub-pixels on the first substrate and alternately arranged with the first common electrodes, color filter layers in the first, second and third sub-pixels on the second substrate, a plurality of viewing angle restricting sub-pixels including fourth, fifth and sixth sub-pixels defined on the first and second substrates, the fourth, fifth and sixth sub-pixels corresponding one-to-one with the first, second and third sub-pixels, second pixel electrodes in the fourth, fifth and sixth sub-pixels on the first substrate, and second common electrodes in the fourth, fifth and sixth sub-pixels on the second substrate.

This application is a Divisional of application Ser. No. 11/639,228,filed Dec. 15, 2006. This invention claims the benefit of Korean PatentApplication No. 10-2005-0133550 filed in Korea on Dec. 29, 2005, whichis hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the invention relates to a display device, and moreparticularly, to a liquid crystal display device and a method of drivingthe same. Although embodiments of the invention are suitable for a widescope of applications, they are particularly suitable for restrictingviewing angle.

2. Discussion of the Related Art

Generally, a liquid crystal display (LCD) includes a first substrate, asecond substrate, and a layer of liquid crystal molecules. The first andsecond substrates face each other and are spaced apart from each other.The layer of liquid crystal molecules is interposed therebetween. TheLCD device uses optical anisotropy and polarization properties of liquidcrystal molecules to display images.

The liquid crystal molecules have orientation characteristics resultingfrom their thin long shape. Thus, an arrangement direction of the liquidcrystal molecules can be controlled by applying an electrical fieldacross the liquid crystal molecules. A thin film transistor (TFT) can beused as a switching element to control application of the electricfield. An LCD device using a TFT is referred to as an active matrix LCD(AM-LCD) device, which has excellent characteristics of high resolutionand being able to smoothly display moving images.

A related art LCD device includes a first substrate, a second substrateand a layer of liquid crystal molecules. The first substrate includes apixel electrode, and the second substrate includes a color filter layerand a common electrode. The first and second substrates face each other,and the layer of liquid crystal molecules is interposed therebetween.The related art LCD device displays images using a vertical electricfield between the pixel and common electrodes. The LCD device using thevertical electric field has a high transmittance and a high apertureratio.

The LCD device using the vertical electric field has the problems ofnarrow viewing angle and low contrast ratio. To resolve theabove-mentioned problems, new display devices, such as an in-planeswitching (IPS) mode LCD device, a vertical alignment (VA) mode LCDdevice and a fringe field switching mode LCD device can be used insteadof a vertical electric field LCD. These LCD devices are explained inreference to FIGS. 1 to 3.

FIG. 1 is a cross-sectional view of an IPS mode LCD device according tothe related art. As shown in FIG. 1, the IPS mode LCD device includesfirst and second substrates 10 and 20 and a layer of liquid crystalmolecules 30 interposed therebetween. The first substrate 10 includespixel and common electrodes 12 and 14 such that a horizontal electricfield 40 is induced between the pixel and common electrodes 12 and 14using voltages applied to the pixel and common electrodes 12 and 14. TheIPS mode LCD device uses the horizontal electric field 40 to displayimages. Since there is little variance in the refractive index of theliquid crystal molecules in the light transmission path while switchingthe IPS mode LCD device, a wide viewing angle is maintained.

FIG. 2A is a cross-sectional view of a VA mode LCD device according tothe related art. As shown in FIG. 2A, the VA mode LCD device includesfirst and second substrates 10 and 20 and a layer of liquid crystalmolecules 30 interposed therebetween. The pixel and common electrodes 12and 24 are formed on the first and second substrates 10 and 20,respectively. A pixel electrode slit 12 a and a common electrode slit 14a are formed on the pixel and common electrodes 12 and 24, respectively.An electric field 50 induced between the pixel and common electrodes 12and 24 is distorted by the pixel electrode slit 12 a and the commonelectrode slit 14 a such that first and second oblique electric fields50 a and 50 b are formed. As a result, the VA mode LCD device has twodomains that result in a wide viewing angle.

FIG. 3 is a cross-sectional view of an FES mode LCD device according tothe related art. As shown in FIG. 3, the FES mode LCD device includesfirst and second substrates 10 and 20 and a layer of liquid crystalmolecules 30 interposed therebetween. The common electrode 14, a gateinsulating layer 16 and a plurality of pixel electrodes 12 having a barshape are sequentially formed on the first substrate 10. The commonelectrode 14 is formed over the entire surface of the first substrate10. The plurality of pixel electrodes 12 are separated from each other.The gate insulating layer 16 between the common electrode 14 and thepixel electrodes 12 prevents a short between the common and pixelelectrodes 14 and 12. Since the pixel and common electrodes 12 and 14are formed on the first substrate and of different layers, a fringefield 60 is formed between the pixel and common electrodes 12 and 14.The fringe field 60 has a reverse U-shape. Since the reverse U-shape hasa flat top portion, the FES mode LCD device functions like the VA modeLCD device so as to have a wide viewing angle.

The above-mentioned LCD devices having a wide viewing angle that alsoresolves the problems of color shift and gray inversion at side viewingangles. A wide viewing angle is useful in that many users at differentviewing angles can observe the same image. However, there are situationsin which only one viewer should see the image. For example, a personusing an automatic teller machine should be the only person able to viewthe image. In this case, the viewing angle should restricted. A methodof restricting the viewing angle with a filter has been used in thepast. However, the filter method increases production time andproduction costs of the LCD device as well as dims the brightness of thedisplay.

SUMMARY OF THE INVENTION

Accordingly, embodiments of the invention are directed to a liquidcrystal display device that substantially obviates one or more of theproblems due to limitations and disadvantages of the related art.

An object of the present invention is to provide a liquid crystaldisplay device that selectively restricts viewing angle.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. Theobjectives and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described herein, aliquid crystal display device includes first and second substratesfacing each other, a layer of liquid crystal molecules interposedbetween the first and second substrates, a plurality of color displayingsub-pixels including first, second and third sub-pixels defined on thefirst and second substrates, first common electrodes in the first,second and third sub-pixels on the first substrate, first pixelelectrodes in the first, second and third sub-pixels on the firstsubstrate and alternately arranged with the first common electrodes,color filter layers in the first, second and third sub-pixels on thesecond substrate, a plurality of viewing angle restricting sub-pixelsincluding fourth, fifth and sixth sub-pixels defined on the first andsecond substrates, the fourth, fifth and sixth sub-pixels correspondingone-to-one with the first, second and third sub-pixels, second pixelelectrodes in the fourth, fifth and sixth sub-pixels on the firstsubstrate, and second common electrodes in the fourth, fifth and sixthsub-pixels on the second substrate.

In another aspect of embodiments of the invention, a liquid crystaldisplay device includes first and second substrate facing each other, alayer of liquid crystal molecules interposed between the first andsecond substrates, a plurality of color displaying sub-pixels includingfirst, second and third sub-pixels and defined on the first and secondsubstrates, first pixel electrodes in the first, second and thirdsub-pixels on the first substrate, color filter layers in the first,second and third sub-pixels on the second substrate, first commonelectrodes on the color filter layers, first and second slits on thefirst pixel electrodes and the first common electrodes, respectively, aplurality of viewing angle restricting sub-pixels including fourth,fifth and sixth sub-pixels and defined on the first and secondsubstrates, the fourth, fifth and sixth sub-pixels correspondingone-to-one with the first, second and third sub-pixels, second pixelelectrodes in the first, second and third viewing angle restrictingsub-pixels on the first substrate, second common electrodes in thefourth, fifth and sixth sub-pixels on the second substrate, and thirdand fourth slits in the second pixel electrodes and the second commonelectrodes, respectively, wherein the first and second slits arealternately arranged with and parallel to each other, and wherein thethird and fourth slits are alternately arranged with and parallel toeach other.

In another aspect of embodiments of the invention, a method of driving aliquid crystal display device including first, second and third colordisplaying sub-pixels and first, second and third viewing anglerestricting sub-pixels, wherein the first, second and third colordisplaying sub-pixels correspond to one-to-one with the first, secondand third viewing angle restricting sub-pixels, and wherein the first,second and third color displaying sub-pixels includes first and secondelectrodes, and the first, second and third viewing angle restrictingsub-pixels includes third and fourth electrodes, includes applying firstand second voltages to the first and second electrodes in each of thefirst, second and third color displaying sub-pixels and third and fourthvoltages to the third and fourth electrodes in each of the first, secondand third viewing angle restricting sub-pixels, wherein the third andfourth voltages are same as each other; and applying fifth and sixthvoltages to the first and second electrodes in each of the first, secondand third color displaying sub-pixels and seventh and eighth voltages tothe third and fourth electrodes in each of the first, second and thirdviewing angle restricting sub-pixels, wherein the third and fourthvoltages are different from each other.

In another aspect of embodiments of the invention, a method of driving aliquid crystal display device including first, second and third colordisplaying sub-pixels and first, second and third viewing anglerestricting sub-pixels, wherein the first, second and third colordisplaying sub-pixels correspond to one-to-one with the first, secondand third viewing angle restricting sub-pixels, and wherein the first,second and third color displaying sub-pixels includes first and secondelectrodes, and the first, second and third viewing angle restrictingsub-pixels includes third, fourth and fifth electrodes, includesapplying first and second voltages to the first and second electrodes ineach of the first, second and third color displaying sub-pixels andthird and fourth voltages to the third and fourth electrodes in each ofthe first, second and third viewing angle restricting sub-pixels,wherein the third and fourth voltages correspond to the first and secondvoltages, respectively; and applying fifth and sixth voltages to thefirst and second electrodes in each of the first, second and third colordisplaying sub-pixels and seventh and eighth voltages to the third andfifth electrodes in each of the first, second and third viewing anglerestricting sub-pixels, wherein the third and fourth voltages aredifferent from each other.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

In the drawings:

FIG. 1 is a cross-sectional view of an IPS mode LCD device according tothe related art;

FIG. 2A is a cross-sectional view of a VA mode LCD device according tothe related art;

FIG. 3 is a cross-sectional view of an FES mode LCD device according tothe related art;

FIGS. 4A and 4B are plane views showing an array substrate and a colorfilter substrate for a viewing angle restricting LCD device according toa first exemplary embodiment of the invention, respectively;

FIG. 5 is a cross-sectional view taken along line V-V of FIGS. 4A and4B;

FIG. 6 is a graph showing a light transmittance property in a viewingangle restricting sub-pixel of a viewing angle restricting LCD deviceaccording to embodiments of the invention;

FIGS. 7A and 7B show properties of color luminance and a gray level in acolor displaying sub-pixel of a viewing angle restricting LCD deviceaccording to embodiments of the invention;

FIGS. 7C and 7D show properties of color luminance and a gray level in acolor displaying sub-pixel and a viewing angle restricting sub-pixel ofa viewing angle restricting LCD device according to embodiments of theinvention;

FIGS. 8A to 8C are plane views showing a viewing angle restricting LCDdevice according to second to fourth exemplary embodiments of theinvention;

FIGS. 9A and 9B are plane views showing an array substrate and a colorfilter substrate for a viewing angle restricting LCD device according toa fifth exemplary embodiment of the invention, respectively;

FIG. 10 is a cross-sectional view taken along line X-X of FIGS. 9A and9B;

FIGS. 11A and 11B are plane views showing an array substrate and a colorfilter substrate for a viewing angle restricting LCD device according toa sixth exemplary embodiment of the invention, respectively; and

FIG. 12 is a cross-sectional view taken along line XII-XII of FIGS. 11Aand 11B.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments,examples of which are illustrated in the accompanying drawings.

FIGS. 4A and 4B are plane views respectively showing an array substrateand a color filter substrate for a viewing angle restricting LCD deviceaccording to a first exemplary embodiment of the invention and FIG. 5 isa cross-sectional view taken along line V-V of FIGS. 4A and 4B. FIG. 6is a graph showing a light transmittance property in a viewing anglerestricting sub-pixel of a viewing angle restricting LCD deviceaccording to embodiments of the invention.

As shown in FIGS. 4A, 4B and 5, a viewing angle restricting LCD deviceaccording to embodiments of the invention includes first and secondsubstrates 110 and 150 and a layer of liquid crystal molecules 130interposed therebetween. A unit pixel, which includes first to thirdcolor displaying sub-pixels CSP1, CSP2 and CSP3 and first to thirdviewing angle restricting sub-pixels VSP1, VSP2 and VSP3, is defined onthe first and second substrates 110 and 150. The first to third colordisplaying sub-pixels CSP1, CSP2 and CSP3 correspond one-to-one with thefirst to third viewing angle restricting sub-pixels VSP1, VSP2 and VSP3.The first to third color displaying sub-pixels CSP1, CSP2 and CSP3 aresequentially arranged as a column in the unit pixel, and the first tothird viewing angle restricting sub-pixels VSP1, VSP2 and VSP3 aresequentially arranged in a second column in the unit pixel.

The first substrate 110 includes gate lines GL, data lines DL, and thinfilm transistors (TFTs) T. The gate and data lines GL and DL cross eachother to define each sub-pixel CSP1, CSP2, CSP3, VSP1, VSP2 and VSP3.The TFTs T are respectively formed in each sub-pixel CSP1, CSP2, CSP3,VSP1, VSP2 and VSP3 and connected to the gate and data lines GL and DL.The second substrate 150 includes a black matrix BM corresponding to thegate and data lines GL and DL, and the TFT T.

A first common line Vom1, first common electrodes 152 and first pixelelectrodes 112 are formed in the first to third color displayingsub-pixels CSP1, CSP2 and CSP3 on the first substrate 110. The firstcommon lines Vcom1 are parallel to the gate line GL and separated fromthe gate line GL. A first common voltage is applied onto the firstcommon electrodes 152 through the first common lines Vcom1. The firstcommon electrodes 152 extend from the first common lines Vcom1 formedbetween the color displaying sub-pixels CSP1, CSP2 and CSP3. The firstpixel electrodes 112 are connected to the TFTs T in the color displayingsub-pixels CSP1, CSP2 and CSP3. The first common electrodes 152 and thefirst pixel electrodes 112 are alternately arranged with each other andparallel to each other. The first common electrodes 152 and the firstpixel electrodes 112 have a bent bar shape. Moreover, the gate and datalines GL and DL can also have the bent bar shape. The viewing anglerestricting LCD device having the first common electrodes 152 and thefirst pixel electrodes 112 with the bent bar shape has multiple domainssuch that the viewing angle is improved. In the alternative, the firstcommon electrodes 152 and the first pixel electrodes 112 may have alinear bar shape.

When voltages are applied across the first pixel electrodes 112 and thefirst common electrodes 152, horizontal electric fields are inducedbetween the first pixel electrodes 112 and the first common electrodes152. The layers of liquid crystal molecules 130 are driven by thehorizontal electric fields. Different voltages generate different graylevels.

A color filter layer CF having red, green and blue colors is formed inthe first to third color displaying sub-pixels CSP1, CSP2 and CSP3 onthe second substrate 150. The first color displaying sub-pixel CSP1 onthe second substrate 150 corresponds to the first color displayingsub-pixel CSP1 on the first substrate 110. The second color displayingsub-pixel CSP2 on the second substrate 150 corresponds to the secondcolor displaying sub-pixel CSP2 on the first substrate 110. The thirdcolor displaying sub-pixel CSP3 on the second substrate 150 correspondsto the third color displaying sub-pixel CSP3 on the first substrate 110.

Second pixel electrodes 114 are formed in the first to third viewingangle restricting sub-pixels VSP1, VSP2 and VSP3 on the first substrate110. The second pixel electrodes 114 are connected to TFTs T in thefirst to third viewing angle restricting sub-pixels VSP1, VSP2 and VSP3.Moreover, second common lines Vcom2 and second common electrodes 154 areformed in the first to third viewing angle restricting sub-pixels VSP1,VSP2 and VSP3 on the second substrate 150. The first viewing anglerestricting sub-pixel VSP1 on the first substrate 110 corresponds to thefirst viewing angle restricting sub-pixel VSP1 on the second substrate150. The second viewing angle restricting sub-pixel VSP2 on the firstsubstrate 110 corresponds to the second viewing angle restring sub-pixelVSP2 on the second substrate 150. The third viewing angle restrictingsub-pixel VSP3 on the first substrate 110 corresponds to the thirdviewing angle restring sub-pixel VSP3 on the second substrate 150.

A second common voltage is applied onto the second common electrodes 154through the second common lines Vcom2. The second pixel electrodes 114and the second common electrodes 154 can each have plate shapes thatrespectively cover the first to third viewing angle restrictingsub-pixels VSP1, VSP2 and VSP3 on the first and second substrates 110and 150, respectively. The second common voltage may be applied to thesecond common electrodes 154 by additional lines in a non-display regionwithout the second common line Vcom2.

When the same voltage is applied onto the second pixel electrode 114 andthe second common electrode 154 of a sub-pixel, the layer of liquidcrystal molecules 130 is not driven such that the sub-pixel displays ablack image. When a voltage is applied across the second pixel electrode114 and the second common electrode 154 of a sub-pixel, the layer ofliquid crystal molecules 130 is driven by a vertical electric fieldbetween the second pixel electrode 114 and the second common electrode154 such that the sub-pixel has maximum transmittance of white light atside viewing angles.

The liquid crystal molecules in the liquid crystal layer 130 can bealigned to have an angle of either 90 degrees or 270 degrees withrespect to the gate lines GL. The first and second polarizers (notshown) having first and second optical axes, respectively, are disposedon outer surfaces of the first and second substrates 110 and 150. Thefirst and second optical axes can be oriented at 0 degree and 90 degreeswith respect to the gate lines GL, respectively. Accordingly, the firstand second optical axes are perpendicular to each other.

When the first and second optical axes are perpendicular to each otherand the liquid crystal molecules 130, which have an initial alignment ofeither 90 degrees or 270 degrees, are driven by the oblique electricfields between the first pixel electrodes 112 and the first commonelectrodes 152, the first to third color displaying sub-pixels CSP1,CSP2 and CSP3 have a wide viewing angle for displaying the image. Thedriving of the layers of liquid crystal molecules 130 in the first tothird viewing angle restricting sub-pixels VSP1, VSP2 and VSP3 isdetermined by voltages applied onto the second pixel electrodes 114 andthe second common electrodes 154 such that the first to third viewingangle restricting sub-pixels VSP1, VSP2 and VSP3 can selectivelyrestrict the viewing angle.

In an ON state, in which the same voltages are applied onto the secondpixel electrodes 114 and the second common electrodes 154, the first tothird viewing angle restricting sub-pixels VSP1, VSP2 and VSP3 have amaximum transmittance at 60 degrees from the front viewing angle and aminimum transmittance at the front viewing angle. In a left directionand a right direction from a point having the maximum transmittance, thefirst to third viewing angle restricting sub-pixels VSP1, VSP2 and VSP3have transmittance but less than the maximum transmittance. In an OFFstate, in which voltages are applied across the second pixel electrodes114 and the second common electrodes 154, the first to third viewingangle restricting sub-pixels VSP1, VSP2 and VSP3 have about zerotransmittance in all viewing angles. In this case, a voltage differencebetween voltages applied across the second pixel electrodes 114 and thesecond common electrodes 154 may be less than 3 V.

Since the first to third viewing angle restricting sub-pixels VSP1, VSP2and VSP3 display black images in all viewing angles in the OFF state,the first to third color displaying sub-pixels CSP1, CSP2 and CSP3display images in all viewing angles without the image being affected bythe first to third viewing angle restricting sub-pixels VSP1, VSP2 andVSP3. On the other hand, the first to third viewing angle restrictingsub-pixels VSP1, VSP2 and VSP3 display black images in the front viewingangle and white images in the side viewing angles in the ON state suchthat the first to third color displaying sub-pixels CSP1, CSP2 and CSP3do not clearly display images in the side viewing angles due to thefirst to third viewing angle restricting sub-pixels VSP1, VSP2 and VSP3corrupting the side viewing angles with white images while the first tothird color displaying sub-pixels CSP1, CSP2 and CSP3 display images inthe front viewing angle that are not affected by the first to thirdviewing angle restricting sub-pixels VSP1, VSP2 and VSP3.

When the first to third viewing angle restricting sub-pixels VSP1, VSP2and VSP3 are in the ON state, images from each unit pixel havesubstantially a same luminance at the side viewing angles. Accordingly,differences of luminance in the first to third color displayingsub-pixels CSP1, CSP2 and CSP3 in the side viewing angles arecompensated by the white luminance of first to third viewing anglerestricting sub-pixels VSP1, VSP2 and VSP3 in the side viewing anglessuch that the side viewing angles are restricted. As a result, only aperson at the front viewing angle can observe the image, while a personat a side viewing angle can not observe the image.

The above-mentioned viewing angle restricting LCD device has the firstto third color displaying sub-pixels CSP1, CSP2 and CSP3 driven byhorizontal electric fields. Further, the first to third viewing anglerestricting sub-pixels VSP1, VSP2 and VSP3 are driven by verticalelectric fields. However, the first to third color displaying sub-pixelsCSP1, CSP2 and CSP3 and the first to third viewing angle restrictingsub-pixels VSP1, VSP2 and VSP3 may be driven by another types of fields.

As shown in FIG. 5, first gate insulating layers 122 are formed betweenthe first common electrodes 152 and the data lines DL, and second gateinsulating layers 124 are formed between the data lines DL and the firstpixel electrodes 112. However, the first common electrodes 152 and thefirst pixel electrodes 112 may be formed in a same layer as each otherwithout one of the first and second gate insulating layers 122 and 124.

In reference to FIGS. 7A to 7D, the above-mentioned compensation effectswill be explained. FIGS. 7A and 7B show properties of color luminanceand a gray level in a color displaying sub-pixel of a viewing anglerestricting LCD device according to embodiments of the invention. FIGS.7C and 7D show properties of color luminance and a gray level in a colordisplaying sub-pixel and a viewing angle restricting sub-pixel of aviewing angle restricting LCD device according to embodiments of theinvention.

As shown in FIGS. 7A and 7B, first to third images have differentluminances from each other. Each of the first to third images includesred, green and blue colors R, G and B. Moreover, the first to thirdimages may have different gray levels. Accordingly, when the liquidcrystal device of the invention is in viewing angle restricting mode, inwhich the first to third viewing angle restricting sub-pixels VSP1, VSP2and VSP3 are in the ON state, it is possible to observe images havingdifferent gray levels at the front viewing angle in spite of the firstto third viewing angle restricting sub-pixels VSP1, VSP2 and VSP3. Thus,the first to third viewing angle restricting sub-pixels VSP1, VSP2 andVSP3 displays white images according to the gray level of the imagesfrom the first to third color displaying sub-pixels CSP1, CSP2 and CSP3.The first to third viewing angle restricting sub-pixels VSP1, VSP2 andVSP3 are controlled such that the images from the first to third colordisplaying sub-pixels CSP1, CSP2 and CSP3 at a side viewing angle have asame gray level as a standard gray level.

As shown in FIGS. 7C and 7D, the LCD device displays fourth to sixthimages having different luminances depending on their colors. Theluminances of red, green and blue colors R, G and B in the fourth imagecorrespond to the luminances of red, green and blue colors R, G and B inthe first image in FIGS. 7A and 7B, and the luminances of red, green andblue colors R, G and B in the fifth image correspond to the luminancesof red, green and blue colors R, G and B in the second image in FIGS. 7Aand 7B. Moreover, the luminances of red, green and blue colors R, G andB in the sixth image correspond to the luminances of red, green and bluecolors R, G and B in the third image in FIGS. 7A and 7B. The images ofwhite color W have different luminances depending on the images from thefourth to sixth images. As mentioned above, the images of white colorare displayed from the first to third viewing angle restrictingsub-pixels VSP1, VSP2 and VSP3, and the fourth to sixth images aredisplayed from the first to third color displaying sub-pixels CSP1, CSP2and CSP3.

The driving method mentioned above is explained in more detail withFIGS. 7C and 7D. As shown in FIG. 7C, first to third white colors W1, W2and W3 correspond to red, green and blue color images R, G and B. Whenthe red, green and blue colors R, G and B have a same luminance as eachother as the fourth image in FIG. 7C, the first to third viewing anglerestricting sub-pixels VSP1, VSP2 and VSP3 are driven so that the firstto third white colors W1, W2 and W3 in the fourth images have a sameluminance as each other. In other words, when the red color R hasluminance greater than the blue color B and less than the green color Gas the fifth image, the first to third viewing angle restrictingsub-pixels VSP1, VSP2 and VSP3 are driven so that the first white colorW1 has luminance greater than the second white color W2 and less thanthe third white color W3. When the red color R has a luminance, which issame as the green color G and greater than the blue color B, as thesixth image, the first to third viewing angle restricting sub-pixelsVSP1, VSP2 and VSP3 are driven so that the first white color W1 has aluminance, which is same as the second white color W2 and less than thethird white color W3.

When the first to third viewing angle restricting sub-pixels VSP1, VSP2and VSP3 are driven by the above-mentioned method, the fourth to sixthimages have different luminances depending on their colors. However, thefourth to sixth images appear to have substantially the same gray levelwhen viewed at side viewing angles. In other words, as shown in FIG. 7D,the gray levels of the second and third images shift up and down suchthat the fourth to sixth images have the same gray level at side viewingangles. Accordingly, the LCD device according to embodiments of theinvention having and driving as mentioned above displays images havingsubstantially the same gray level to improve the effect of restrictingthe side viewing angles.

When the TFTs T in the first to third color displaying sub-pixels CSP1,CSP2 and CSP3 are turned on, the layers of liquid crystal molecules 130are driven by the horizontal electric fields induced between the firstpixel electrodes 112 and the first common electrodes 152 to displayimages having a wide viewing angle. When the TFTs T in the first tothird viewing angle restricting sub-pixels VSP1, VSP2 and VSP3 areturned on, the layers of liquid crystal molecules 130 are driven by thevertical electric fields induced between the second pixel electrodes 114on the first substrate 110 and the second common electrodes 154 on thesecond substrate 150. When voltages are applied across the second pixelelectrodes 114 and the second common electrodes 154, the first to thirdviewing angle restricting sub-pixels VSP1, VSP2 and VSP3 do not displaythe white color into the front viewing angle but do emit light into theside viewing angles. Thus, the images from the first to third colordisplaying sub-pixels CSP1, CSP2 and CSP3 at the side viewing angles arecorrupted by the first to third viewing angle restricting sub-pixelsVSP1, VSP2 and VSP such that the viewing angles at the sides arerestricted. Thus, the LCD device according to embodiments of theinvention has a narrow viewing angle mode.

On the other hand, when the same voltage is applied onto the secondpixel electrodes 114 and the second common electrodes 154, the first tothird viewing angle restricting sub-pixels VSP1, VSP2 and VSP3 do notdisplay the white color at the side viewing angles so that the image canbe observed in all viewing angles from the first to third colordisplaying sub-pixels CSP1, CSP2 and CSP3. In this case, the first tothird viewing angle restricting sub-pixels VSP1, VSP2 and VSP3 do notrestrict viewing angles. Thus, the LCD device according to embodimentsof the invention also has a wide viewing angle mode.

The LCD device according to embodiments of the invention hasconvertibility between wide and narrow viewing angle modes depending onthe first to third viewing angle restricting sub-pixels VSP1, VSP2 andVSP3 being turned on. Although not shown, the LCD device may include agray level determining unit, a luminance detecting unit and a luminancecompensating unit. The gray level determining unit determines thestandard gray level. The luminance detecting unit detects luminances ofthe images displayed in the first to third color displaying sub-pixelsCSP1, CSP2 and CSP3. The luminance compensating unit determinesluminances of the white color in the first to third viewing anglerestricting sub-pixels VSP1, VSP2 and VSP3 depending on the luminance ofthe images detected by the luminance detecting unit. The voltages, whichare applied onto the second pixel electrodes 114 in the first to thirdviewing angle restricting sub-pixels VSP1, VSP2 and VSP3, are determinedby the luminance compensating unit.

FIGS. 8A to 8C are plane views showing a viewing angle restricting LCDdevice according to second to fourth exemplary embodiments of theinvention, respectively. The LCD devices in FIGS. 8A to 8C include aunit pixel. The unit pixel includes the first to third color displayingsub-pixels CSP1, CSP2 and CSP3 and the first to third viewing anglerestricting sub-pixels VSP1, VSP2 and VSP3. As mentioned above, thefirst to third viewing angle restricting sub-pixels VSP1, VSP2 and VSP3display white colors depending on the images from the first to thirdcolor displaying sub-pixels CSP1, CSP2 and CSP3.

As shown in FIG. 8A, in the viewing angle restricting LCD deviceaccording to the second exemplary embodiment of the invention, the firstto third color displaying sub-pixels CSP1, CSP2 and CSP3 are alternatelyarranged with one another in (2N−1)th rows, and the first to thirdviewing angle restricting sub-pixels VSP1, VSP2 and VSP3 are alternatelyarranged with one another in (2N)th rows where N is a positive integer.When the viewing angle restricting sub-pixels VSP1, VSP2 and VSP3 havetoo small area, the LCD device does not have a sufficient viewing anglerestricting function. However, when the viewing angle restrictingsub-pixels VSP1, VSP2 and VSP3 have too broad an area, the LCD devicehas a decreased aperture ratio and decreased luminance. Considering theviewing angle restricting function and the aperture ratio, area of theviewing angle restricting sub-pixels VSP1, VSP2 and VSP3 can be between10 percent and 50 percent of the area of the unit pixel.

FIGS. 8B and 8C show the viewing angle restricting LCD device having animproved aperture ratio. As shown in FIG. 8B, in the viewing anglerestricting LCD device according to the third exemplary embodiment ofthe invention, the first to third color displaying sub-pixels CSP1, CSP2and CSP3 are alternately arranged with one another in (3N−2)th rows and(3N)th rows, and the viewing angle restricting sub-pixels VSP1, VSP2 andVSP3 are alternately arranged with one another in (3N−1)th rows.Moreover, as shown in FIG. 8C, in the viewing angle restricting LCDdevice according to the fourth exemplary embodiment of the invention,the first to third color displaying sub-pixels CSP1, CSP2 and CSP3 arealternately arranged with one another in (3N−2)th columns and (3N)thcolumns, and the viewing angle restricting sub-pixels VSP1, VSP2 andVSP3 are alternately arranged with one another in (3N−1)th columns. InFIGS. 8B and 8C, one viewing angle restricting sub-pixel matches withtwo color displaying sub-pixels such that area occupied by the viewingangle restricting sub-pixels is decreased. As a result, the apertureratio and luminance are improved.

FIGS. 9A and 9B are plane views showing an array substrate and a colorfilter substrate for a viewing angle restricting LCD device according toa fifth exemplary embodiment of the invention, respectively, and FIG. 10is a cross-sectional view taken along the line X-X of FIGS. 9A and 9B.As shown in FIGS. 9A, 9B and 10, the viewing angle restricting LCDdevice includes first and second substrates 210 and 250 facing eachother, and a layer of liquid crystal molecules 230 interposedtherebetween. The unit pixel, which includes the first to third colordisplaying sub-pixels CSP1, CSP2 and CSP3 and the first to third viewingangle restricting sub-pixels VSP1, VSP2 and VSP3, is defined on thefirst and second substrates 210 and 250. The first to third colordisplaying sub-pixels CSP1, CSP2 and CSP3 correspond one-to-one with thefirst to third viewing angle restricting sub-pixels VSP1, VSP2 and VSP3.The first to third color displaying sub-pixels CSP1, CSP2 and CSP3 aresequentially arranged in a first column of the unit pixel, and the firstto third viewing angle restricting sub-pixels VSP1, VSP2 and VSP3 aresequentially arranged in a second column of the unit pixel.

The first substrate 210 includes gate lines GL, data lines DL, and TFTsT. The gate and data lines GL and DL cross each other to define eachsub-pixel CSP1, CSP2, CSP3, VSP1, VSP2 and VSP3. The TFTs T arerespectively formed in the each sub-pixel CSP1, CSP2, CSP3, VSP1, VSP2and VSP3 and connected to the gate and data lines GL and DL. Firstinsulating layers 222 may be formed between the gate lines GL and thedata lines DL, and second insulating layers 224 may be formed on thedata lines DL. The second substrate 250 includes a black matrix BMcorresponding to the gate and data lines GL and DL, and the TFT T.

First slits 212 a are formed in the first pixel electrodes 212 in thefirst to third color displaying sub-pixels CSP1, CSP2 and CSP3 on thefirst substrate 210. The first slits 212 a have a bent bar shape. Thefirst slits 212 a can have angles of either 45 degrees or 315 degreeswith respect to the gate lines GL.

The color filter layer CF is formed in the first to third colordisplaying sub-pixels CSP1, CSP2 and CSP3, and the first commonelectrode areas 252 is formed on the color filter layer CF. The colorfilter layer CF includes red, green and blue colors. Second slits 252 ahaving the bent bar shape are formed in the first common electrode areas252. The second slits 252 a are alternately arranged with the firstslits 212 a and parallel to the first slits 212 a.

The first and second slits 212 a and 252 a have the bent bar shape, asshown in FIGS. 9A and 9B. In the alternative, the first and second slits212 a and 252 a may have a linear bar shape. Moreover, the data linesDL, the first pixel electrodes 212 and the first common electrode areas252 may have a same bent bar shape as the first and second slits 212 aand 252 a. The sub-pixels have a mono-domain in the case of the linearbar shape. The sub-pixels have multiple domains in the case of the bentbar shape have a wider viewing angle.

When voltages are applied across the first pixel electrodes 212 and thefirst common electrode areas 252, the electric fields induced betweenthe first pixel electrodes 212 and the first common electrode 252 areasare distorted by the first and second slits 212 a and 252 a such thatoblique electric fields are formed. The layer of liquid crystalmolecules 230 is driven by the oblique electric fields such that theviewing angle is improved. The oblique electric fields cross the firstand second slits 212 a and 252 a such that the liquid crystal molecules230 are arranged depending on the oblique electric fields and have anangle of either 45 degrees or 315 degrees with respect to the gate linesGL. When the first and second slits 212 a and 252 a have the linear barshape, in which the first and second slits are parallel to the datalines DL, the liquid crystal molecules are parallel to the gate linesGL.

Second pixel electrodes 214 are formed in the first to third viewingangle restricting sub-pixels VSP1, VSP2 and VSP3 on the first substrate210, the second common electrode areas 254 corresponding to the secondpixel electrodes 214 is formed in the first to third viewing anglerestricting sub-pixels VSP1, VSP2 and VSP3 on the second substrate 250.Third slits 214 a, which are parallel to the gate lines GL and have alinear bar shape, are formed in the second pixel electrodes 214, andfourth slits 254 a, which are parallel to the third slits 214 a andalternately arranged with the third slits 214 a, are formed in thesecond common electrode areas 254.

When voltages are applied across the second pixel electrodes 214 and thesecond common electrodes 254, electric fields are induced between thesecond pixel electrodes 214 and the second common electrode area 254 aredistorted by the third and fourth slits 214 a and 254 a such that theelectric fields become oblique. The oblique electric fields cross thethird and fourth slits 214 a and 254 a such that the liquid crystalmolecules 230 are arranged depending on the oblique electric fields andcan have an angle of 0 degree with respect to the data lines DL. Inother words, the liquid crystal molecules 230 are arranged to beperpendicular to the gate lines GL. Since the oblique electric fields inthe first to third viewing angle restricting sub-pixels VSP1, VSP2 andVSP3 are perpendicular to the gate lines GL, the first to third viewingangle restricting sub-pixels VSP1, VSP2 and VSP3 have a transmittance of0 percent in the front viewing angle. Certain side viewing angles to theleft and right of the front viewing angle have increased transmittancesuch that the first to third viewing angle restricting sub-pixels VSP1,VSP2 and VSP3 have a maximum transmittance. Further to the left andright sides from the certain viewing angles having the maximumtransmittance, the transmittance decreases. The certain viewing anglescan be 60 degrees from the front viewing angle.

The liquid crystal molecules in the liquid crystal layer 130 can bealigned to have an angle of either 90 degrees or 270 degrees withrespect to the gate lines GL. First and second polarizers (not shown)having first and second optical axes, respectively, are disposed onouter surfaces of the first and second substrates 110 and 150. The firstand second optical axes can be either 0 degrees or 90 degrees withrespect to the gate lines, respectively. Accordingly, the first andsecond optical axes are perpendicular to each other.

When the first and second optical axes are perpendicular to each otherand the liquid crystal layer 130, which has an initial alignment of oneof 90 degrees and 270 degrees, is driven by the electric fields betweenthe first pixel electrodes 212 and the first common electrode areas 252,the first to third color displaying sub-pixels CSP1, CSP2 and CSP3 havea wide viewing angle. When voltages are applied across the second pixelelectrodes 214 and the second common electrode areas 254, the first tothird viewing angle restricting sub-pixels VSP1, VSP2 and VSP3 displaythe white color at side viewing angles and do not display the whitecolor at the front viewing angle such that the users in the side viewingangles do not observe the images from the first to third colordisplaying sub-pixels CSP1, CSP2 and CSP3 at the side viewing angles.Accordingly, the viewing angle restricting LCD device can have a narrowviewing angle mode.

When the same voltage is applied onto the second pixel electrodes 214and the second common electrode areas 254, the first to third viewingangle restricting sub-pixels VSP1, VSP2 and VSP3 have substantially 0percent transmittance at all viewing angles such that the users at allviewing angles can observe the images from the first to third colordisplaying sub-pixels CSP1, CSP2 and CSP3. Accordingly, the viewingangle restricting LCD device also has a wide viewing angle mode. As aresult, the viewing angle restricting LCD device of the above-describedfifth exemplary embodiment has convertibility between the wide andnarrow viewing angle modes.

In the above-mentioned fifth exemplary embodiment, the first to fourthslits 212 a, 252 a, 214 a, 254 a have different shapes with theabove-mentioned shapes depending on the alignment direction of theliquid crystal molecules and the optical axes of the first and secondpolarizers (not shown). Moreover, the first to third color displayingsub-pixels CSP1, CSP2 and CSP3 and the first to third viewing anglerestricting sub-pixels VSP1, VSP2 and VSP3 may be driven as shown inFIGS. 7A to 7D.

FIGS. 11A and 11B are plane views showing an array substrate and a colorfilter substrate for a viewing angle restricting LCD device according toa sixth exemplary embodiment of the invention, respectively, and FIG. 12is a cross-sectional view taken along the line XII-XII of FIGS. 11A and11B. As shown in FIGS. 11A, 11B and 12, the viewing angle restrictingLCD device includes first and second substrates 310 and 350 facing eachother, and a layer of liquid crystal molecules 330 interposedtherebetween. The unit pixel, which includes the first to third colordisplaying sub-pixels CSP1, CSP2 and CSP3 and the first to third viewingangle restricting sub-pixels VSP1, VSP2 and VSP3, is defined on thefirst and second substrates 310 and 350. The first to third colordisplaying sub-pixels CSP1, CSP2 and CSP3 correspond one-to-one with thefirst to third viewing angle restricting sub-pixels VSP1, VSP2 and VSP3.The first to third color displaying sub-pixels CSP1, CSP2 and CSP3 aresequentially arranged in a first column of the unit pixel, and the firstto third viewing angle restricting sub-pixels VSP1, VSP2 and VSP3 aresequentially arranged in a second column of the unit pixel.

The first substrate 310 includes gate lines GL, data lines DL, and TFTsT. The gate and data lines GL and DL cross each other to define eachsub-pixel CSP1, CSP2, CSP3, VSP1, VSP2 and VSP3. The TFTs T arerespectively formed in each of the sub-pixel CSP1, CSP2, CSP3, VSP1,VSP2 and VSP3 and connected to the gate and data lines GL and DL. Firstinsulating layers 322 may be formed between the gate lines GL and thedata lines DL. Second insulating layers 324 and third gate insulatinglayers 326 can be sequentially formed on the data lines DL. The secondsubstrate 350 includes the black matrix BM corresponding to the gate anddata lines GL and DL, and the TFTs T.

The first common electrodes 352 have a plate shape and are respectivelyformed on the first substrate 310 over the first to third colordisplaying sub-pixels CSP1, CSP2 and CSP3. The first common electrodes352 can be formed between the second and third gate insulating layers324 and 326. The first pixel electrodes 312, which have a bent bar shapeand are connected to the TFTs T, are formed on the third gate insulatinglayers 326 in the first to third color displaying sub-pixels CSP1, CSP2and CSP3. The first pixel electrodes 312 having the bent bar shape canhave angles of either 45 degrees or 315 degrees with respect to the gatelines GL. The color filter layer CF is formed on the second substrate350 in the first to third color displaying sub-pixels CSP1, CSP2 andCSP3. The color filter CF includes red, green and blue colors.

The first pixel electrodes 312 having the bent bar shape are shown inFIG. 11A. In the alternative, the first pixel electrode 312 can have alinear bar shape. Moreover, the data lines DL can have the same bent barshape as the first pixel electrodes 312. The first to third colordisplaying sub-pixels CSP1, CSP2 and CSP3 have a mono-domain in the caseof the linear bar shape. The first to third color displaying sub-pixelsCSP1, CSP2 and CSP3 have multiple domains in the case of the bent barshape that results in a wide viewing angle.

When voltages are applied across the first pixel electrodes 312 and thefirst common electrodes 352, some liquid crystal molecules 330 aredriven by fringe electric fields induced between the first pixelelectrodes 312 and the first common electrodes 352 such that the viewingangle is widened. The fringe electric fields have the reverse U-shape.Other liquid crystal molecules 330 are driven by horizontal electricfields, which corresponds to a flat top surface of the fringe electricfields.

First common electrodes 352 are formed on the first substrate 310 in thefirst to third viewing angle restricting sub-pixels VSP1, VSP2 and VSP3.The first common electrodes 352 have a plate shape and respectivelycover the surfaces of the first to third viewing angle restrictingsub-pixels VSP1, VSP2 and VSP3. The first common electrodes 352 may beformed on the second gate insulating layer 324 s on the first substrate310. Second pixel electrodes 314 are formed over the first commonelectrodes 352. The second pixel electrodes 314 are connected to theTFTs T in the first to third viewing angle restricting sub-pixels VSP1,VSP2 and VSP3 and have the bent bar shape. Third gate insulating layers326 can be interposed between the first common electrodes 352 and thesecond pixel electrodes 314. The second common electrodes 354 are formedon the second substrate 350 in the first to third viewing anglerestricting sub-pixels VSP1, VSP2 and VSP3. The second common electrode354 can have the plate shape such that the second common electrodes 354cover surfaces of the first to third viewing angle restrictingsub-pixels VSP1, VSP2 and VSP3. The second pixel electrode 314 havingthe bent bar shape can have an angle of either 45 degrees or 315 degreeswith respect to the gate lines GL.

Similar to the first pixel electrodes 312, the second pixel electrodes314 can have a linear bar shape. Moreover, the data lines DL may havethe same bent bar shape as the second pixel electrodes 314. Thesub-pixels each have a mono-domain in the case of the linear bar shape.On the other hand, the sub-pixels have multiple domains in case of thebent bar shape such that the viewing angle is widened.

The first to third viewing angle restricting sub-pixels VSP1, VSP2 andVSP3 are driven by using different electrodes depending on their modes.In the wide viewing angle mode, the second pixel electrodes 314 and thefirst common electrodes 352 are used to drive the layers of liquidcrystal molecules 330 in the first to third viewing angle restrictingsub-pixels VSP1, VSP2 and VSP3. However, in the narrow viewing anglemode, the first common electrodes 352 and the second common electrodes354 are used to drive the layers of liquid crystal molecules 330 in thefirst to third viewing angle restricting sub-pixels VSP1, VSP2 and VSP3.

When voltages are applied across the second pixel electrodes 314 and thefirst common electrodes 352 in the wide viewing angle mode, the layersof liquid crystal molecules 330 are driven by the fringe electric fieldinduced between the second pixel electrodes 314 and the first commonelectrodes 352. In this case, a same voltage as the first commonelectrode 352 is applied into the second common electrode 354 such thatan electric field is not induced between the first and second commonelectrodes 352 and 354. In other words, in the wide viewing angle mode,the layers of liquid crystal molecules 330 are driven by the fringeelectric field between the second pixel electrodes 314 and the firstcommon electrodes 352 such that images are displayed to all viewingangles. The luminances of the white colors from the first to thirdviewing angle restricting sub-pixels VSP1, VSP2 and VSP3 correspond tothe luminance of the images from the first to third color displayingsub-pixels CSP1, CSP2 and CSP3 such that luminances of the first tothird viewing angle restricting sub-pixels VSP1, VSP2 and VSP3compensate the images from the first to third color displayingsub-pixels CSP1, CSP2 and CSP3. Accordingly, the luminance property inthe wide viewing angle mode is improved. When the first to third viewingangle restricting sub-pixels VSP1, VSP2 and VSP3 do not include thesecond pixel electrode 324 and the same voltage is applied into thefirst and second common electrodes 352 and 354, the first to thirdviewing angle restricting sub-pixels VSP1, VSP2 and VSP3 display theblack color. As a result, the luminance and the aperture ratiodeteriorate. However, since the first to third viewing angle restrictingsub-pixels VSP1, VSP2 and VSP3 include the second pixel electrode 314,the LCD device does not have the above-mentioned problems.

In the narrow viewing angle mode, voltages are applied across the firstand second common electrodes 352 and 354 such that the liquid crystallayer 330 is driven by the vertical electric field induced between thefirst and second common electrodes 352 and 354. In this case, the samevoltage as the first common electrode 352 is applied into the secondpixel electrode 314 such that an electric field is not induced betweenthe second pixel electrode 314 and the first common electrode 352. Thefirst to third viewing angle restricting sub-pixels VSP1, VSP2 and VSP3display the white color at side viewing angles. Accordingly, the imagesform the first to third color displaying sub-pixels CSP1, CSP2 and CSP3is damaged by the white color such that the viewing angle is restricted.The first to third viewing angle restricting sub-pixels VSP1, VSP2 andVSP3 has a transmittance of 0% in the front viewing angle. As it goesleft and right sides from the front viewing angle, the transmittanceincreases to a certain viewing angle. As it goes left and right sidesfrom the certain side viewing angle, the transmittance decreases.Accordingly, the first to third viewing angle restricting sub-pixelsVSP1, VSP2 and VSP3 have a maximum transmittance at the certain sideviewing angle. The maximum transmittance may be about 100%.

To obtain the above-mentioned transmittance properties, the liquidcrystal molecules can be aligned to have an angle of either 90 degreesor 270 degrees with respect to the gate lines GL. The first and secondpolarizers (not shown) having first and second optical axes,respectively, are disposed on outer surfaces of the first and secondsubstrates 310 and 350. The first and second optical axes can be 0degree or 90 degrees with respect to the gate lines, respectively.Accordingly, the first and second optical axes are perpendicular to eachother. When the first and second optical axes are perpendicular to eachother and the liquid crystal molecules 330, which have an initialalignment of either 90 degrees or 270 degrees, is driven by the fringeelectric field between the first pixel electrodes 312 and the firstcommon electrodes 352, the first to third color displaying sub-pixelsCSP1, CSP2 and CSP3 have a wide viewing angle.

The luminance of the first to third viewing angle restricting sub-pixelsVSP1, VSP2 and VSP3 enhance or corrupt the images from the first tothird color displaying sub-pixels CSP1, CSP2 and CSP3 at the sideviewing angles depending on the mode. In more detail, when voltages,which correspond to the voltages applied into the first to third colordisplaying sub-pixels CSP1, CSP2 and CSP3, are applied across the secondpixel electrodes 314 and the first common electrodes 352, the viewingangle restricting LCD device is in the wide viewing angle mode. On theother hand, when voltages are applied into the first and second commonelectrodes 352 and 354, the viewing angle restricting LCD device is in anarrow viewing angle mode. As a result, the viewing angle restrictingLCD device according to the sixth exemplary embodiment of the inventionhas convertibility between the wide and narrow viewing angle modes. Thedriving method described with FIGS. 7A to 7D may be applied into theviewing angle restricting LCD device according to the sixth exemplaryembodiment of the invention.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the substrate for the liquidcrystal display device and the method of fabricating the same of theinvention without departing from the spirit or scope of the invention.Thus, it is intended that the present invention covers the modificationsand variations of this invention provided they come within the scope ofthe appended claims and their equivalents.

1. A method of driving a liquid crystal display device including first, second, and third color displaying sub-pixels and first, second, and third viewing angle restricting sub-pixels, the first, second, and third color displaying sub-pixels corresponding one-to-one with the first, second, and third viewing angle restricting sub-pixels, the first, second, and third color displaying sub-pixels including first and second electrodes, and the first, second, and third viewing angle restricting sub-pixels include third and fourth electrodes, the method comprising: in a first viewing mode, applying first voltages to the first and second electrodes, respectively, in each of the first, second, and third color displaying sub-pixels and the same first voltages to the third and fourth electrodes, respectively, in each of the first, second, and third viewing angle restricting sub-pixels; and in a second viewing mode, applying second voltages to the first and second electrodes, respectively, in each of the first, second, and third color displaying sub-pixels and different third voltages to the third and fourth electrodes, respectively, in each of the first, second and third viewing angle restricting sub-pixels.
 2. The method according to claim 1, wherein the first, second and third electrodes are formed on the first substrate and the fourth electrode is formed on the second substrate.
 3. The method according to claim 1, wherein the first and third electrodes are formed on the first substrate and the second and fourth electrodes are formed on the second substrate.
 4. The method according to claim 1, wherein the viewing angle restricting images have a minimum luminance at a front viewing angle and a maximum luminance at a side viewing angle different from the front viewing angle.
 5. The method according to claim 1, wherein the first voltages are the same as the second voltages.
 6. The method according to claim 1, wherein the first voltages are different from the second voltages.
 7. A method of driving a liquid crystal display device including first, second, and third color displaying sub-pixels and first, second, and third viewing angle restricting sub-pixels, the first, second, and third color displaying sub-pixels corresponding to one-to-one with the first, second, and third viewing angle restricting sub-pixels, the first, second, and third color displaying sub-pixels including first and second electrodes, and the first, second, and third viewing angle restricting sub-pixels include third, fourth and, fifth electrodes, comprising: in a first viewing mode, applying first voltages to the first and second electrodes, respectively, in each of the first, second, and third color displaying sub-pixels and the same first voltages to the third and fourth electrodes, respectively, in each of the first, second, and third viewing angle restricting sub-pixels, the voltage applied to the third electrode and the voltage applied to the fourth electrode corresponding to the voltage applied to the first electrode and the voltage applied to the second electrode, respectively; and in a second viewing mode, applying second voltages to the first and second electrodes, respectively, in each of the first, second, and third color displaying sub-pixels and different third voltages to the third and fifth electrodes, respectively, in each of the first, second, and third viewing angle restricting sub-pixels.
 8. The method according to claim 7, wherein the viewing angle restricting images have a minimum luminance at a front viewing angle and a maximum luminance at a side viewing angle different from the front viewing angle.
 9. The method according to claim 7, wherein the first voltages are the same as the second voltages.
 10. The method according to claim 7, wherein the first voltages are different from the second voltages. 